Vehicle steering systems comprise steering locks to safeguard against theft, said steering locks being fitted with a device for disabling a rotational movement of a steering shaft where necessary. Traditionally, a locking member of the steering lock that can be moved into a release or locking position is brought into engagement with a locking sleeve rigidly secured to the steering shaft. For locking, the locking bolt engages with a latching element of a sleeve secured to the steering shaft. In order to release the lock, the locking bolt moves out of the latching element of the sleeve and thereby allows the steering shaft or the steering wheel to move again.
As described in WO 2010/035127 A1, tolerance rings are used in the state of the art in steering columns to connect the steering wheel lock to the steering wheel shaft. In this case, the tolerance ring is held about the shaft circumference by a latching element which is engaged with the steering wheel lock in the locked state. When the steering wheel lock is in the unlocked state, the tolerance ring is rotated with the latching element in an unimpeded manner, so that the driver is able to steer the car. At the same time, the tolerance rings are configured in such a manner that they prevent the steering wheel lock from being prized open. Via tolerance rings, high torques act on the shaft and the latching element. Above a threshold value, the shaft and the latching element can slip relative to one another. If the steering column is located in the locked state during unauthorized use of the vehicle, the motor vehicle cannot be properly steered. At the same time, damage to the steering column is prevented. The disadvantages of using a tolerance ring of this kind are that considerable effort is required in order to achieve a defined threshold value of the torque between the shaft and the latching element. In this case, it may be necessary for two tolerance rings to be used or grooves worked into the shaft.
DE 100 12 323 A1 discloses a locking sleeve for a steering column which is formed by a profiled pipe section which is provided with grooves. The grooves have projecting and recessed regions on the outside of the pipe section which interact with a bolt of a locking mechanism and the tires have contact surfaces with the steering column on the inside. The locking sleeve is pushed onto the steering column by force. The disadvantage of this solution is that the form of the locking sleeve is not sufficiently flexible to allow a latching element to be pushed onto the steering column with force and, at the same time, to absorb manufacturing tolerances to an adequate degree. Moreover, the geometry of the locking sleeve means that it is not possible for a precise defined and reproducible threshold value of the torque to be achieved between the shaft and the latching element.
EP 1 568 554 A1 discloses a method for producing a locking sleeve which is formed by deformation into a tubular sleeve body with a hollow profile in cross section with a joint. At each joint, a closed hollow body is formed with a connection element. The forming of the projections may take place through a forming action without machining, such as deep-drawing, for example. The rolling-in of the sleeve body may take place over multiple forming or bending steps. The disadvantage of this production method is that cracks can occur with high natural strains, particularly in the bending radii.
Thus a need exists for a latching star wheel for a steering lock of a motor vehicle that has good torsional properties and thereby provides a reproducibly defined threshold value for the torque between the shaft and latching element and, in addition, can be produced in the simplest and most cost-effective way possible.